Uniform velocity thruster



Sept. 15, 1959 c. c. FAwcETT ETAL 2,903,849

UNIFORM VELOCITY THRUSTER Filed April 1o, 1958 FIG. I.

INVENT EGIL C. FAWCE BER L. T M. STOTT CRESTON F. LAAGER we. MM/ 52 13M# A WM FIG. 2.

United States Patent O UNIFORM VELOCITY THRUSTER Cecil C. Fawcett, Huntingdon Valley, and Albert M. Stott, Aldan-Clifton Heights, Pa., and Creston F. Laager, Beverly, NJ., assignors to the United States of America as represented by the Secretary of the A-lmy Application April 10, 1958, Serial No. 727,748

3 Claims. (Cl. 60-19) (Granted under Title 35, U.S. lCode (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of 'any royalty thereon.

This invention relates to thrusters such as are used to move a man-seat mass in a moving aircraft, and more particularly to an improved thrusterof the type disclosed in a copending application of Albert M. Stott and Herbert A. Magnus, Ser. No. 644,426 iiled March 6, 1957 now Patent No. 2,857,889 issued Oct. 28, 1958 for One Stroke Thruster With Speed Reducer.

In the thruster disclosed by the aforesaid application, a cartridge actuated piston operates a second piston through a liquid coupling. A check Valve on the second piston allows liquid to ow into a restricted space ahead of the second piston for cushioning and controlling its movement. When this second piston moves, the check valve closes and the liquid ahead of it is discharged through a small opening which determines to a large extent the speed of the piston and the force exerted by it.

The device of the present invention dilers from that disclosed by the aforesaid application in that (l) the two pistons are arranged side by side instead of end to end and (2) the relation between the two pistons is so moditied that the operating gas is applied to the second piston at the end of the stroke of the gas operated piston. This arrangement has the important advantage that it utilizes more efliciently the energy generated by the firing of the cartridge.

The invention will be better understood from the following description when considered in connection with the accompanying drawings and its scope is indicated by the appended claims.

Referring to the drawings:

Fig. l is a sectional view of a preferred form of the invention, and

Fig. 2 is an end view of the device illustrated by Fig. l.

This device includes a cylinder and a cylinder 11 which are joined together at their adjacent sides. The cylinder 10 encloses a piston 13 which is integr-al with a rod 14 and has a longitudinal aperture 15. The rod 14 is adapted to be coupled to the load and is held in its illustrated position by a shear pin 16. Seal rings 17 'and 18 surround the rod 14 and the piston 13, and the right hand end of the cylinder 10 is closed by a plug 19.

The cylinder 11 is closed at its right hand end by a plug 20. Adjacent to -this plug is a chamber 21 adapted to enclose a receptacle made of rubber or very thin aluminum and filled with silicone oil. At the left hand end of the cylinder 11 is a tiring pin 22 which is held in its illustrated position by a shear pin 23 interposed between it and a collar 24, this collar being fixed in position by a locking ring 25. The collar 24 and the firing pin 22 are surrounded by seal rings 26 and 27. G-as for operating ICC the tiring pin 22 is applied through an opening 35 in the collar 24.

Adjacent the inner end of Ithe collar 24 is a cartridge 28 arranged to be activated by the iiring pin 22. Interposed between the cartridge 28 and the chamber 21 is a floating piston 29 which is surrounded by a seal ring 30, has a skirt 31 and has a plurality of perforations 32. In the final position `of the piston 29 the perforations 32 open into a passageway 33 leading into the cylinder 10.

Mounted within the piston 13 is a check valve similar to that disclosed by the above-mentioned application. This check valve includes a ball 34 which is biased to its illustrated `closed position by a spring 36. The ball 34 Iand spring 36 are supported in a collar 37 which is threaded into the rod 14, is locked in position by ya suitable vlocking plug 38 and has openings 39 in an undercut which communicate with similar openings in the rod 14.

With -this arrangement, firing ofthe cartridge 28 drives the piston 29 to the right, rupturing the oil container in the chamber 21 and forcing oil through the passage 33 into the cylinder 10 and through the valve 34-36 and openings 39 into the restricted space between the rod 14 and the cylinder 10.

When the pressure attains a predetermined value, the pin 16 shears, `and the piston 13 starts to move at a rate dependent on how fast the oil between the rod 14 and the cylinder 10 is discharged through the opening 15, the rate of this discharge being determined by the size of the opening 15. When the piston 29 reaches the end of its travel, gas under pressure is applied through the openings 32 and the passageway 33 to the piston 13.

Thus by placing the two cylinders side by side, instead of end to end as in the case of aforesaid application and providing the openings in the skirt of the oating piston, the energy generated by the tiring of the cartridge is more fully utilized and the structure of the [dev-ice is made lighter and more compact.

We claim:

l. The combination of a first cylinder enclosing a first piston iixed to a rod extensible from lsaid cylinder, a pressure responsive valve arranged to provide an opening through said first piston into said first cylinder in response to pressure, means forming through said lirst piston an opening of a lsize dependent on the speed at which said iirst piston is to -be moved, a second cylinder having at one end a liquid retaining chamber and at the other end means for generating a gas pressure, means forming a passageway from said chamber to said rst cylinder at the rear of said iirst piston, and a iloating piston interposed between said chamber and pressure `generating means and operable at the end of its travel to admit gas to said lirst cylinder.

2. A combination -according to claim 1 wherein said floating piston has a trailing skirt with a perforation arranged to be alined with said passageway only near the end of the travel of said floating piston.

3. A combination according to claim l wherein said chamber encloses a liquid amd said pressure is applied through said liquid to said first piston during the travel of said oating piston and is yapplied directly to said first piston near the end of said travel.

References Cited in the tile of this patent UNITED STATES PATENTS 2,396,778 Flowers Mar. 19, 1946 2,728,538 Mazis Dec. 27, 1955 2,857,889 Stott et al Oct. 28, 1958 

